This project will continue to characterize the enzyme defects in galactosemia due to gal-l-P uridylyltransferase deficiency. An improved enzyme purification procedure is under development using isoelectric focussing. Procedures have been developed for analyzing specific components of the transferase reaction, that can be used to study the specific perturbation of various galactosemic mutations. Characterization of galactosemic cell differences, from patient to patient, will utilize immunochemical methods to study the electrophoretic and quantitative differences in this cell protein in both red cells and cultured fibroblasts from patients with galactosemia. The kinetics of transferase synthesis and degradation will be analyzed in cell culture.